Cool!

What is the behavior of the following?

And(x > 0, y > 1).as_set()

Note that Set.as_relational doesn't handle this either. I just want to make sure that we raise a suitable error or that the answer is not ambiguous.

Should this be implemented using a _as_set to dispatch. @mrocklin what's the advantage of doing it that way rather than just using as_set directly?

What is the behavior of the following?

And(x > 0, y > 1).as_set()

At the time you commented it was giving the wrong result as (0, oo). Now I have modified the code to raise a suitable error. I have also added a XFAIL to test to remind us of future work.

At the time you commented it was giving the wrong result as (0, oo)

No. But, perhaps, it does matter in which order I have run the above statements.

Now I have modified the code to raise a suitable error.

Which one? I don't see any difference:

In [1]: And(x>0, y>1).as_set()
Out[1]: (1, ∞)

In [2]: Or(x>0, y>1).as_set()
Out[2]: (0, ∞)

At the time you commented it was giving the wrong result as (0, oo)

No. But, perhaps, it does matter in which order I have run the above statements.

Sorry but I couldn't understand your comment. What I meant was that the code was buggy the time Matthew asked for the result of And(x>0, y>1).as_set(). Then I amended the commit to fix it.

The code on my system is raising the correct error (with an unintentional typo). I don't know why we are getting different results. See the lines of code which raises error here: https://github.com/sympy/sympy/pull/2781/files#diff-cf47a176c69dd7d5e3225858891e091cR288

from sympy import *

from sympy.abc import x, y

And(x>0, y>1).as_set()
---------------------------------------------------------------------------
NotImplementedError                       Traceback (most recent call last)
<ipython-input-3-c4a8716c2ceb> in <module>()
----> 1 And(x>0, y>1).as_set()

/home/hargup/arbit_sympy_testing/sympy/logic/boolalg.pyc in as_set(self)
    286             return Intersection(*[arg.as_set() for arg in self.args])
    287         else:
--> 288             raise NotImplementedError("Sorry, And.as_set has not yet been"
    289                                       " implemented for mutivariate"
    290                                       " expressions")

NotImplementedError: Sorry, And.as_set has not yet been implemented for mutivariate expressions

Or(x>0, y>1).as_set()
---------------------------------------------------------------------------
NotImplementedError                       Traceback (most recent call last)
<ipython-input-4-9d432be651cb> in <module>()
----> 1 Or(x>0, y>1).as_set()

/home/hargup/arbit_sympy_testing/sympy/logic/boolalg.pyc in as_set(self)
    348             return Union(*[arg.as_set() for arg in self.args])
    349         else:
--> 350             raise NotImplementedError("Sorry, Or.as_set has not yet been"
    351                                       " implemented for mutivariate"
    352                                       " expressions")

NotImplementedError: Sorry, Or.as_set has not yet been implemented for mutivariate expressions

On Fri, Jan 17, 2014 at 05:00:39AM -0800, Harsh Gupta wrote:

The code on my system is raising the correct error (with an unintentional
typo). I don't know why we are getting different results.

Sorry. That was my bad, perhaps, I've not run git fetch.

Should this be implemented using a _as_set to dispatch. @mrocklin what's the advantage of doing it that way rather than just using as_set directly?

I mostly followed tradition. The benefits I've seen though are shared docstrings and the ability to enforce code at the superclass level (see Set.contains)

There was a typo in 'multivariate', I have fixed it.

Travis is being timed out. Is there anything that I do about it?

Thanks. This is in.